Neuroplasticity
Neuroplasticity refers to the brain's remarkable ability to reorganize itself by forming new neural connections in response to various factors such as injury, environmental changes, or sensory input. This adaptability allows the brain to compensate for damages—such as rerouting tasks typically managed by one area of the brain to another—while also facilitating the development of new skills and the enhancement of memory in healthy individuals. Historically, it was believed that the brain's neural connections were fixed after early childhood, but advances in research, particularly from the 1960s onward, demonstrated that these connections can continue to evolve throughout a person's life.
Neuroplasticity can manifest positively, aiding recovery from brain injuries and improving cognitive functions through mental exercises. Interestingly, it can also lead to phenomena like phantom limb sensations or tinnitus, indicating the brain's attempts to adapt to changes, such as the loss of a limb or hearing. Engaging in activities that stimulate the brain—like learning new skills or participating in social interactions—can promote neuron growth and enhance mental abilities, even as one ages. While the brain's capacity for change remains intact throughout life, distractions and irrelevant information can hinder the effectiveness of this process. Overall, neuroplasticity underscores the brain's potential for growth and adaptation, reflecting its complexity and resilience.
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Subject Terms
Neuroplasticity
Neuroplasticity is the ability of the human brain to "rewire" itself by establishing new neural connections in response to injury, developmental or environmental changes, or changes in sensory input. The brain is a complex organ responsible for mental functions such as memory and emotions; it also controls the central nervous system and provides operating instructions to other organs in the body. It is divided into several sections, each responsible for a specific function. Scientists have discovered that the brain can adapt to changes by physically altering its structure to reorganize these functions. This "plastic" capability of the brain can be used to compensate for injuries and illness by rerouting tasks normally assigned to one section of the brain to another. It can also help maintain and strengthen healthy brains by developing new skills and improving memory.
Background
The average human brain weighs about three pounds and makes up about 2 percent of a person's body weight. Compared to other vertebrates, humans have the largest brains relative to their body size. The brain is one of the most vital organs in the body, acting as both a source of mental activity and the command center for operating the body's other organs and systems. The brain does this through a network of billions of nerve cells called neurons. Neurons communicate with each other by transmitting electrical and chemical signals that contain specific information or instructions the body needs to function. The parts of the neuron that transmit these messages are nerve fibers called axons and dendrites. Axons transmit electrical impulses away from the neuron, and dendrites act as receivers for the impulses. The brain and central nervous system contain trillions of connections that send or receive information along a specific neural pathway, or network.
Neurons go about their tasks in a brain divided into several sections, each responsible for a specific function in the body. The cerebrum, the largest and outermost section of the brain, is separated into two hemispheres and contains the cerebral cortex, the area responsible for complex thought. The cerebral cortex itself is divided into four lobes, each of these managing its own tasks such as visual processing, memory, language, sensory perception, and emotion. The two hemispheres of the brain control functions on the opposite side of the body; for instance, the left area of the brain controls the right side of the body and the right area controls the left. Other, deeper sections of the brain control basic tasks such as hunger, sleep, balance, and heart and lung functions.
Overview
The idea that the neural connections in the human brain develop over time is a concept that dates back to the nineteenth century. Researchers, however, thought that these changes occurred only in early childhood. The connections of the adult brain were believed to have been fully formed and locked into place. In the early twentieth century, pioneering neuroscientist Santiago Ramón y Cajal suggested some "neuronal plasticity" was possible in adults, but his ideas were often disputed by other scientists. In the 1960s, technological advances such as magnetic resonance imaging (MRI) and electron microscopy allowed researchers to observe the brain in more detail. They discovered that neural pathways did continue to evolve into adulthood and the process continued through a person's lifetime.
Research into neuroplasticity, as the field was called, increased in the late twentieth century, leading scientists to reexamine previous notions about the brain. It had long been accepted that injured or damaged nerve cells could not be regenerated; however, scientists found that undamaged axons could regrow nerve endings to repair a damaged neural pathway. Axons could also grow nerve endings to reestablish connections with undamaged neurons, bypassing the injured section of the brain and rerouting the transmission of electrochemical information. For example, a person who experienced an injury to the language center in the left hemisphere of the brain may have language functions taken over by the right hemisphere. The effectiveness of the process depends on the severity of the injury and can be aided with rehabilitation. Sometimes neuroplasticity may have negative effects, such as a deaf person who develops a constant ringing in the ears. This is a sign that the body is trying to rewire the brain to compensate for the lack of sound. It is also responsible for the phantom limb phenomenon, in which amputees feel pain or sensation in an arm or leg that has been removed.
Neuroplasticity can also play a role in improving the function of healthy brains through mental stimulation and brain workouts. Human cognitive ability tends to peak between the ages of twenty and thirty. As people get older, memory, attention, and learning skills begin to decline. The brain's "plastic" capabilities, however, do not deteriorate with age. By performing specific mental exercises focusing on sensory input, movement, and cognitive patterns, people can stimulate neuron growth and improve brain function. These tests may include identifying different colored objects from only a brief glimpse, recognizing whether a sound is increasing or decreasing in frequency, or finding a pattern in a sequence of symbols. Researchers have also found that simple activities such as physical activity, learning a skill, or interacting in new social situations have a positive effect on mental ability.
Brains stimulated by mental exercises tend to be more alert and motivated, two conditions that can increase the production of neurochemicals that facilitate neuron growth. Practicing the exercise and focusing on the task increase its effectiveness; distractions and irrelevant mental clutter can slow or impair the process. While initial progress is sometimes temporary, the brain can remember positive results and build upon them to make more lasting changes. In time, enhancing certain brain connections can also diminish activity in others, reducing distractions and increasing the ability to focus.
Bibliography
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